Patient information sheet

Condition

Intervention

Supplementation is provided for six months from October to March. There is no additional follow-up. However there is a run-in phase during the preceding summer when participants are asked to keep a diary of sun exposure and activities outdoors. This is assessed in July and August.

Overall trial start date

Overall trial end date

Reason abandoned (if study stopped)

Eligibility

Participant inclusion criteria

1. Consenting adult men and women2. Aged 20 - 85 years3. In general good health

Participant type

Patient

Age group

Adult

Gender

Both

Target number of participants

240 from Coleraine and 240 from Cork

Participant exclusion criteria

1. Severe medical illness2. Hypercalcaemia3. Known intestinal malabsorption syndrome4. Excessive alcohol use5. Those who took medications known to interfere with vitamin D metabolism6. Pregnancy or planning to become pregnant during the six months of the intervention7. Those taking high dose vitamin D-containing supplements for three months before initiation of study8. Those who over the six-month course of intervention are planning a winter vacation to a location at which either the altitude or the latitude would be predicted to result in significant cutaneous vitamin D synthesis from solar radiation (e.g., a mountain ski resort or a winter sun coastal resort)